\begin{tikzpicture}[>=Stealth,
    every node/.style={fill=white, inner sep=1pt},
]
    \pgfmathsetmacro{\factor}{0.2}
    \draw [->] (-0.5, 0) -- (5.5, 0) node[right=0.1] {$t$(时)}  coordinate(x axis);
    \draw [->] (0, -0.5) -- (0, 3.5) node[left=0.2em] {$T$(℃)} coordinate(y axis);
    \draw (0, 0) coordinate(O) node [below left] {\small $0$};
    \foreach \x in {2, 4, ..., 24} {
        \draw (\factor * \x, 0.1) -- (\factor * \x, 0) node [below] {\small $\x$};
    }
    \foreach \y in {2, 4, ..., 14} {
        \draw (0.1, \factor * \y) -- (0, \factor * \y) node[left] {\small $\y$};
    }

    \coordinate (a) at ($\factor*(0, 5)$);
    \coordinate (b) at ($\factor*(4, 1.8)$);
    \coordinate (c) at ($\factor*(14, 11.8)$);
    \coordinate (d) at ($\factor*(24, 7)$);

    % 随意绘制的曲线
    \draw
        (a) to [bend left] (b)
        plot [smooth] coordinates{
            (b)
            ($\factor*(6, 3.3)$)
            ($\factor*(8, 4.2)$)
            ($\factor*(10, 6.0)$)
            ($\factor*(10.5, 7.5)$)
            ($\factor*(12, 9.5)$)
            (c)
            ($\factor*(16, 11.7)$)
            ($\factor*(18, 11.5)$)
            ($\factor*(20, 9.8)$)
            ($\factor*(22, 8.5)$)
            (d)
        };

    % 几条辅助线
    \draw [dashed] (b -| y axis) -- (b) -- (b |- x axis);
    \draw [dashed] (c -| y axis) -- (c) -- (c |- x axis);
    \draw [dashed] (d) -- (d |- x axis);
\end{tikzpicture}

